AoC 2022, day 21 (perl part 1)

#!/usr/bin/perl

use strict;
use warnings;

my %monkey;
while (<>) {
    chomp;
    my ($monk, $yell) = split ':';

    if ($yell =~ m#(\d+)#) {
        $monkey{$monk} = [$1];
    } else {
        $yell =~ m#(\w+) (.) (\w+)#;
        $monkey{$monk} = [$2, $1, $3];
    }
}

sub recurse_parse_tree {
    my $monk = shift @_;
    my $node = $monkey{$monk};

    return ($node->[0]) if (@$node == 1);

    my @arg = map { &recurse_parse_tree( $node->[$_] ) } (1 .. 2);

    return (eval "$arg[0] $node->[0] $arg[1]");
}

print "Part 1: ", &recurse_parse_tree( 'root' ), "\n";